ISIS support grows as more Al Shabaab members pledge allegiance

Support for ISIS appears to be growing as a new video, purportedly released by Al Shabaab, shows 50 fighters pledging their allegiance to the radical militant group.

Al Shabaab, the Somalian Islamist group, has previously been an affiliate of al Qaeda who have denounced the so-called Islamic State. However earlier this month a leading Al Shabaab preacher, Sheikh Absulkadir Mumin, pledged his allegiance.

Mumin, who was formerly UK-based, is a powerful charismatic preacher and his switch of allegience is significant as it marks a split in the African extremist group.

Although Al Shabaab's senior leadership remain al Qaeda supporters, the new video shows that Mumin's move has led to a number of younger Al Shabaab fighters also converting to ISIS. Out of an estimated 1,400 members, at least 100 are now thought to be ISIS supporters.

One source close to Al Shabaab explained that these defections are a significant gain for ISIS as their influence spreads out of Iraq and Syria, into west Africa through Boko Haram and now possibly into east Africa.

"The Islamic State has been trying to recruit Somalis and members of Al Shabaab for a while, it helps ISIS colour in their map just that bit more," a Somali intelligence source told CNN.

However many fighters within Al Shabaab remain horrified at ISIS' activities. The group's secret police, known as Amniyat, have been arresting members who it is believed might switch allegience.

"Morally -- I see [ISIS] as a deviant, bloodthisty tyrannical group," said one source close to Al Shabaab to CNN.

"I don't know why I would join them. [ISIS] cannot get us heavy weaponry or fill our ranks with men and expertise due to geographical issues. The only thing we would gain from joining them is momentum."

Although at the moment the split is significant symbolically more than numerically, if the trend continues it could present a real concern for African governments as ISIS' influence grows.